The guilty nine-tailed fox Qingxuan and her immortal servant Hanyu opened the "Demon Collection Office" Ruyilou in Chang'an, dealing with the supervision of the heavens and the weird things in the city. From the conspiracy behind the rat demon who stole official money, to the life-threatening demon fetus spawned by the Guanyin Temple, she got deeper and deeper, but unexpectedly became entangled with Shen Qi, the thoughtful minister of Dali Temple. The two sometimes teamed up to break the situation, and sometimes tested each other. While investigating cases such as the soul-eating gas in the grain stack and the blood sacrifice in the mass grave, they gradually came closer to the ghost's conspiracy to use evil spirits to open up the underworld. Qingxuan must not only hide her identity to complete redemption, but also fight against the encroaching dark forces. The turbulent situation in Chang'an City is pushing her into an ultimate showdown involving life and death.
